Seafood prices on restaurant menus as far back as the 1860s have helped scientists track the impact of over-harvesting on marine species.

They also reveal changing tastes among the restaurant-going public.

The study of US menus held in library and university collections could help inform the conservation of modern stocks, say the authors.

The results will be presented at a conference on the history of marine animal populations in Denmark.

The power of using the menus, is that you can take that relationship from the 1950s to today and extend it back 100 years in time

Glenn Jones Texas A&M University

The researchers looked at National Fisheries Service records going back to the 1950s of seafood landings and their dollar value. They then compared these with the retail prices from the menus.

"There's a very strong correlation between those data sets," said project leader Dr Glenn Jones of Texas A&M University at Galveston, Texas.

"The power of using the menus, is that you can take that relationship from the 1950s to today and extend it back 100 years in time."

Lobster was one of the species looked at by the researchers. Prior to the 1880s, it was unusual to see lobster on menus.

But tastes changed around the beginning of the 20th Century. By the 1950s, prices ballooned, with restaurants pricing lobsters at one-quarter pound (113g) weight increments.

Dr Jones and his colleagues interpret this as a reflection of declining stocks.

Historical ephemera

The study also shows a dramatic rise in the price of abalone coinciding with the collapse of stocks along the Californian coast.

"Abalone has seen a 10-fold rise in its price since the 1920s," Dr Jones told the BBC News website.

The researchers still need to carry out sorting of the five-star restaurants from two-star restaurants, which will give them a more detailed understanding of changing tastes and fluctuations in the price of different species.

Many of the collections were donations by private enthusiasts.

"When you think about it, a menu was a piece of ephemera, it wasn't meant to be saved, but thankfully, some people collected them," said Dr Jones.

"We believe this is the first time anyone has tried to work with this treasure trove of historical information."

The preliminary results will be presented at the Oceans Past conference in Kolding, Denmark, which runs from the 24-27 October.

It has been organised by the Census of Marine Life, a 10-year project to give a baseline assessment of the state of our oceans today.

"To gain a sense of perspective on that, you need a historical counter-image," commented Poul Holm, who leads the History of Marine Animal Populations (HMap) arm of the Census of Marine Life.